Diamond pattern (6)
I believe the answer is:
'diamond pattern' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for argyle that I've seen before include "Diamond knitting pattern" , "Design of diamond-shaped patterns - Plymouth ___, football team" , "See 10" , "Of diamond - patterned material" , "Old Scottish county; part name of a W Country football team" .)